what happens when you try to turn it on? what happens when you do a reset, do you see a dialogue pop up?
To turn on the nook color you need to press and hold the power button for a few seconds, until the screen flickers on. -maybe you are not holding it down long enough?
Mine is doing something simular.
left it on went into sleep mode for a while went to start it up , acting like it's not on so I go to start it up and it flickers, gives me the "read forever" screen then the nook "n" and then nothing.
couple of times it's tried to reset itself.